Use of the Clark Twin Block functional appliance with and without an upper labial bow: a randomized controlled trial.

OBJECTIVES: To compare dentoalveolar and skeletal changes in two groups of Class II division 1 patients treated with different designs of Clark's Twin Block (CTB), with (Group 1) or without (Group 2) an upper labial bow. MATERIALS AND METHODS: A randomized controlled trial was conducted in the Department of Orthodontics at the East Kent Hospitals University NHS Foundation Trust, UK. Sixty-two white subjects (aged 10-14 years at the start of treatment, minimum overjet > 6 mm, molar relationship at least ½ unit Class II) were recruited. Subjects were divided into age- and sex-matched pairs, were randomly allocated to treatment with either appliance design, and were treated for 12 months, at which time additional data were collected. RESULTS: Sixty participants were available for final data collection. The two groups were well matched with respect to age (mean 12.5 years in Group 1; 12.3 years in Group 2). No statistical difference was noted between groups for any dentoalveolar or skeletal variables measured. Both groups experienced a reduction in overjet as a result of maxillary incisor retroclination, mandibular incisor proclination, and forward positioning of the pogonion. Maxillary molar distalization, mandibular molar mesialization, and ANB reduction also occurred in both groups. CONCLUSIONS: The addition of a maxillary labial bow to the CTB has no influence on dentoalveolar or skeletal changes, or on rate of overjet reduction, in relation to appliance therapy.

Pre-eruptive coronal resorption of a maxillary canine: a case report.

This paper is the first to highlight a case of pre-eruptive coronal resorption of a maxillary canine in a patient undergoing extraction-based fixed appliance therapy. The etiology, clinical implications, and management of pre-eruptive coronal resorption are discussed.

Relationship between bilateral congenital absence of maxillary lateral incisors and anterior tooth width.

INTRODUCTION: The objective of this study was to assess the relationship between anterior tooth width and the presence or absence of maxillary lateral incisors. METHODS: Reference models of 106 subjects, 52 with bilateral agenesis of maxillary lateral incisors and 54 fully dentate controls, were examined. The sample was based on orthodontic patients treated over a 10-year period at Kent and Canterbury Hospital, Canterbury, Kent, United Kingdom. Maximum tooth widths were measured by using digital calipers (Tesa Technology, Renens, Switzerland). RESULTS: Individual tooth dimensions in the maxillary and mandibular anterior segments were reduced by 0.33 to 0.42 mm, respectively, in subjects with agenesis of the maxillary lateral incisors. Linear regression analysis confirmed that these differences have statistical significance (P <0.001). CONCLUSIONS: Isolated bilateral absence of maxillary lateral incisors is associated with reduced mesiodistal tooth widths in both the maxillary and mandibular anterior segments.